What larger monitors work with the 15" vga G4 iMac

It is not so much how large but rather a question of resolution and how it would look on a larger monitor than the original.

All iMac G4 15-inchers supported: 640x480; 800x600; and 1024x768 at a fixed 4:3 ratio--no provision for widescreen. The old rule of thumb for decent clarity for 4:3 ratio CRT monitors was:

• 15-inch monitor supports 640x480
• 17-inch supports 800-x600
• 19 to 20 inch supports 1024x768

I believe you would find the same issues with an older 4:3 flat-panel monitor.

Also the iMacs can only mirror the resolution set on the built-in monitor so you can't have the external one set differently nor use it for extended desktop. If you set the built-in to 640x480 (would look nice at 15 inches) you are going to get 640x480 on the external regardless of how big it is. On a 19-20 incher, 640x480 could start to look pixelated.

I think that is a plan. And I fully understand your reasoning; I also have a newer iMac quad-core i7 but I keep a 2003 G4 PowerMac G4 MDD in service in a spare bedroom because it has a working install of Adobe CS2.